Gingival Recession Associated With Predisposing Factors in Young Vietnamese: A Pilot Study

Tung Nguyen-Hieu1, Bao-Dan Ha-Thi2, Hang Do-Thu2, Hoa Tran-Giao3

1PhD, DDS.* † 2MSc, DDS.* 3DDS.* *Department of Periodontology, Faculty of Odonto-Stomatology, University of Medicine and Pharmacy, Ho Chi Minh City, Vietnam. †Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes, UM 63, CNRS 7278, IRD 198, INSERM 1095, Aix-Marseille Université, Marseille, France.

Abstract Aims: Several studies have shown a large diversity in the prevalence, extent and severity of gingival recession as well as controversial conclusions of its associated factors. Therefore, the aim of this pilot study was to evaluate gingival reces- sion with predisposing factors in young Vietnamese. Methods: A cross-sectional study using clinical examination was performed in 120 dental students. Oral hygiene status, tooth malposition and fraenal attachment were recorded. The width of keratinised gingiva was measured after mucosa staining with Lugol’s iodine solution. Measurements of gingival recession were performed on labial tooth surfaces. Chi- square test, t-test and Pearson’s correlation were used for data analysis. Results: The prevalence of gingival recession was 72.5% of the studied population. The extent of affected teeth was 11.1% of the examined teeth. The proportion of root-surface exposure was statistically higher (P<0.05) in the maxilla (12.5%) than in the mandible (9.6%). Premolars and right canines were the teeth most frequently and most seriously associated with gingival recession, respectively. There was a strong negative correlation between narrow width of kera- tinised gingiva and gingival recession (P<0.001). The recession was statistically associated with tooth malposition (P<0.001) but it was not related to high fraenal attachment and gender. Conclusions: A high prevalence of gingival recession was found in Vietnamese dental students. Gingival recession was associated with narrow width of keratinised gingiva, tooth malposition and maxillary teeth. Further studies performed in larger populations with more extended age groups are needed to confirm these findings.

Key Words: Gingival Recession, Prevalence, Severity, Extent, Tooth Malposition, Fraenal Attachment, Keratinised Gingiva

Introduction tooth-brushing, non-carious cervical lesions (abra- Gingival recession has been defined as a displace- sion, abfraction, erosion, resorption), inflammation ment of gingival margin apically from the cemen- (dental plaque, calculus, , periodontitis), to-enamel junction (CEJ), leading to root-surface iatrogenic factors (inappropriate fixed prostheses, exposure, which may cause poor aesthetics, dentine poorly designed partial , operative proce- hypersensitivity, plaque retention, gingival bleed- dures, orthodontic treatment, traumatic ) ing, susceptibility for root caries and fear of tooth and diverse factors (age, gender, piercing, chewing loss [1-3]. A denuded root surface frequently stick trauma) [3,4]. A high prevalence of gingival results from a combination of predisposing and recession has been reported in America (63%-89%) triggering/aggravating factors. Predisposing factors [5-7], Europe (25%-84%) [8-13] and Australia included bone dehiscence, insufficiency of width (71%) [14] but a lower prevalence has been found and/or thickness of keratinised gingiva, tooth mal- in Africa (28%) [15,16] and Asia (15%) [17]. position and high fraenal attachment. The trigger- However, the extent of root-surface exposure was ing/aggravating factors may include: traumatic higher in Africa (18%-51%) [15,16] and America

Corresponding author: Tung Nguyen-Hieu, Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes, Faculté de Médecine, Aix-Marseille Université, 27 boulevard Jean Moulin, 13005 Marseille, France; e-mail : [email protected]

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(38%-44%) [5-7] than in Europe (5%-17%) [8-13], They obtained a kappa index of agreement of more Australia (4.6%) [14] and Asia (2%) [17]. There than 0.8. Oral hygiene status was evaluated by are limited published data concerning the preva- Simplified Oral Hygiene Index (OHI-S) [21]. lence, extent, and severity, as well as associated Labial surfaces of upper first molars and lingual factors of gingival recession in Asia [16,18]. surfaces of lower first molars (sometimes second Furthermore, conclusions of the association molars because of first molar loss) and the labial between gingival recession and predisposing fac- surfaces of upper right and lower left central inci- tors including width of keratinised gingiva [12], sors were assessed for debris and calculus accumu- fraenum attachment [13,18] and tooth malposition lations. The OHI-S has two components including [15,18,19] are still controversial [20]. Although the the Simplified Debris Index (DI-S) and the aetiology of root-surface exposure is multifactorial, Simplified Calculus Index (CI-S), which are based determining the influence of predisposing factors on numerical determinations representing the has an important role in management of gingival amount of debris and calculus found on the select- recession such as increasing keratinised tissue, ed tooth surfaces. Each of these indices has scores fraenectomy or orthodontic treatment. from 0-3 corresponding with an absence of soft debris/calculus, their amount covering one-third, Aim two-thirds, and more than two-thirds of the exam- The aim of this pilot study was to measure gingival ined tooth surface, respectively. recession in a population of 19-25 year-old dental All excluded sites including absent teeth, tooth students for preliminary assessment of the preva- roots and tooth-supported fixed prostheses (crowns lence, extent, severity of gingival recession and its and bridges) were noted. Tooth malpositions predisposing factors including width of keratinised including overeruption, rotation and other gingiva, tooth malposition and fraenal attachment malalignment were also recorded. The position of in Vietnamese young adults. the CEJ was determined by visual observation and the "slight scratch" of a periodontal probe on the Methods cervical tooth area in a cervico-occlusal direction. If there were non-carious cervical (wear) lesions or Target population cervical restorations, the position of the CEJ was A cross-sectional study using a clinical examina- considered as corresponding with that of adjacent tion was performed in a population of 120 dental teeth. Gingival recession was evaluated by using a students of University of Medicine and Pharmacy millimetre-graduated periodontal probe to measure of Ho Chi Minh City in Vietnam. These subjects from the free gingival margin to the CEJ at the site were randomly selected from about 600 students of of maximum gingival recession on the labial sur- Faculty of Odonto-Stomatology. Briefly, 80-120 face of each tooth (excluding third molars). In order dental students from every class were classified to localise the mucogingival junction (MGJ), both into ten groups of 8-12 students, from which two the gingiva and buccal mucosa were rinsed with groups were randomly selected. A total of 12 water, dried and then stained with 3% Lugol's groups including 120 students from six classes iodine solution (3 g of elemental iodine and 6 g agreed to participate in this study after reading the potassium iodine in 300 mL sterile water) by using research objectives and signing a consent form. a cotton swab. After two minutes, highly kera- Only 19-25 year-old students, non-smoking and tinised epithelium did not retain the Lugol's iodine those having more than 24 teeth (excluding third solution while buccal mucosa was stained a red- molars) were included. Students with a history of brown colour. The width of keratinised gingiva of orthodontic or periodontal treatment were exclud- each tooth (excluding third molars and previously ed. The type of toothbrush (soft, medium or hard) excluded sites) was measured by using a millime- used by the students was recorded. tre-graduated periodontal probe from MGJ to free gingival margin with 1.0 mm precision. Fraenal Clinical examination and measurements attachments were also assessed according to the All clinical examinations were performed by two Placek et al. (1974) classification [22] in which periodontists (B-D H-T and H D-T) who had previ- four levels of labial fraenal attachments are mucos- ously calibrated by recording all clinical measure- al, gingival, papillary and papillary penetrating. ments to be used in the study on ten dental students. After clinical examination, participants were given

135 OHDM - Vol. 11 - No. 3 - September, 2012 oral hygiene instruction and advice on how to con- gival recession. The proportion of root denudation trol the progression of gingival recession as well as was statistically higher (chi-square test, P<0.05) in suggestions for appropriate treatment. the maxilla (205/1634, 12.5%) than in the mandible (157/1635, 9.6%). Furthermore, teeth most fre- quently associated with gingival recession were the Data analysis left first molar (35/116, 30.2%) and the right first For assessing the oral hygiene status, OHI-S value premolar (31/114, 27.2%) in the maxilla and the was calculated and classified from 0-1.2 for good right second premolar (24/113, 21.2%) and left first status, 1.3-3.0 for medium status and 3.1-6.0 for premolar (25/119, 21%) in the mandible (Figure 1). poor status. Values of DI-S and CI-S were com- In the maxilla, a decreasing degree of root-surface bined to obtain OHI-S value as follows: DI-S = exposure was observed as follows: premolars (total scores of debris)/(total number of tooth sur- (84/205, 41%) > molars (74/205, 36.1%) > canines faces with debris), CI-S = (total scores of calcu- (34/205, 16.6%) > incisors (13/205, 6.3%). In the lus)/(total number of tooth surfaces with calculus) mandible, this was found as follow: premolars and OHI-S = (DI-S + CI-S) [21]. Descriptive statis- (90/157, 57.3%) > molars (37/157, 23.6%) > inci- tics and the chi-square test were carried out to char- sors (18/157, 11.5%) > canines (12/157, 7.6%). acterise the prevalence, extent, severity of gingival Students with gingival recession had mean recession, and the predisposing factors. In this measurements of denuded root surface from 1.0-1.9 study, the prevalence of gingival recession was the mm in both maxilla and mandible. The most seri- percentage of patients with at least one gingival ous gingival recession was detected at upper right recession in the studied population, the extent was canines (1.9±1.2 mm) and lower right canines the percentage of teeth associated with root-surface (1.9±1.3 mm) (Figure 2). exposure in examined teeth, and the severity was the level of apical migration of marginal gingiva from the CEJ. The Student's t-test was used to com- Predisposing factors associated with gingival pare keratinised gingiva widths between teeth with recession and without root-surface exposure. The correlation Overall, the width of keratinised gingiva was more between keratinised tissue and gingival recession important in the regions of incisors and molars and was assessed by Pearson's correlation coefficient. less important in the regions of canines and premo- These statistical analyses were independently per- lars. Teeth with gingival recession had a greater formed by a specialist using statistical software reduced width of keratinised gingiva than non- (Statistical Package for the Social Sciences, version affected teeth. In particular, these differences were 15.0; SPSS Inc, Chicago, USA). Differences were statistically significant in all premolars (t-test, considered statistically significant when the P- P<0.05) and right canines (t-test, P<0.01) of both value was <0.05. the maxilla and the mandible (Figure 3). A nega- tive correlation was also found between the fre- Results quency of root-surface exposure and width of kera- tinised gingiva (Pearson's correlation, r=-0.33, Prevalence, extent and severity of gingival reces- P<0.001). A narrow width of keratinised gingiva sion (<2 mm according to classification of Maynard and The study group comprised 60 males and 60 Wilson, 1980) [23] was observed in 388 (11.9%) of females with mean age of 22.3±2.0 years. Ninety- the teeth. Teeth with a narrow width of keratinised six (80%) subjects had a good status of oral hygiene gingiva had a higher prevalence of gingival reces- according to the OHI-S value and 116 (97%) sub- sion (111/388, 28.6%) than teeth with a broad jects used soft/medium toothbrushes. The preva- width of attached gingiva (251/2881, 8.7%) and lence of gingival recession (at least one tooth with this difference was statistically significant (chi- denuded root surface >1.0 mm) was 87/120 square test, P<0.001) (Table 1). Gingival/papillary (72.5%). This prevalence was slightly higher in attachments of fraenal (types II, III and IV accord- females (45/60, 75%) than in males (42/60, 70%) ing to classification of Placek et al. (1974) [22]) but this difference was not statistically significant. were only detected at 64 (1.9%) teeth. Teeth with Among a total of 3269 examined teeth (1634 these high fraenal attachments had a lower frequen- teeth in the maxilla and 1635 teeth in the cy of denuded root surface (3/64, 4.7%) than teeth mandible), there were 362 teeth (11.1%) with gin- without this feature (359/3205, 11.2%) but this dif-

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Figure 1. Extent of gingi- val recessions in the max- illa and the mandible.

Figure 2. Severity of gin- gival recession in the max- illa and the mandible

Figure 3. Width of kera- tinised gingiva between teeth with and without gingival recession.(t-test: **:P<0.01; *:P<0.05)

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Table 1. Correlations between gingival recessions and predisposing factors

Predisposing factors Number of teeth (%) P* Without recession With recession Normal width of keratinised gingiva (> 2 mm) 2630 (91.3%) 251 (8.7%) <0.001 Narrow width of keratinised gingiva (< 2 mm) 277 (71.4%) 111 (28.6%) No fraenum/normal fraenal attachments 2846 (88.8%) 359 (11.2%) >0.05 Gingival/papillary fraenal attachments 61 (95.3%) 3 (4.7%) Normal position teeth 2658 (89.9%) 298 (10.1%) <0.001 Tooth malposition 249 (79.6%) 64 (20.4%)

* Chi-square test ference was not statistically significant (chi-square Because poor margins can be a factor in test, P>0.05). The proportion of malpositioned attachment loss and gingival recession [26], sites teeth was 313/3269 (9.6%), of which dental rota- with fixed prostheses were also excluded. Although tion (117/3269, 3.6%) and labial declination several studies have indicated that dental plaque, (67/3269, 2%) were most frequently found. gingival inflammation and calculus were signifi- Malaligned teeth had a higher prevalence of gingi- cantly associated with root-surface exposure val recession (64/313, 20.4%) than normally posi- [7,10,16,18,19], gingival recession more frequently tioned teeth (298/2956, 10.1%) and this difference occurred in patients having good rather than poor was statistically significant (chi-square test, oral hygiene [2,27]. The oral hygiene of dental stu- P<0.001) (Table 1). Of the 362 teeth associated dents who took part in the current study was evalu- with root-surface exposure, 111 (30.7%) teeth had ated by using OHI-S, which may be suitable for a narrow width of keratinised gingiva, 64 (17.7%) subsequent studies assessing oral hygiene and gin- teeth were related to dental malpositions, only 3 gival recession in wider populations of non-dental (0.8%) teeth were associated with high fraenal students. In this pilot study, the majority of dental attachments, and 219 (60.5%) teeth were still non- students had a good level of oral hygiene and their identified aetiology. use of soft/medium toothbrushes suggested that they had high awareness of the need for good oral Discussion health. Therefore, the orodental status of these den- In this study, 19-25 year-old students were includ- tal students almost certainly differs from that of ed because their permanent dentition was relatively young adults in the overall Vietnamese population. complete and the occurrence of gingival recession This is a limitation of the study in that the results had previously been detected in this age group. cannot safely be generalised to all Vietnamese Only subjects without triggering/aggravating fac- young people. However, these preliminary results tors (smoking, orthodontic/periodontitis treatment, can be used as reference for further studies in a periodontal surgery, and fixed prostheses) of gingi- larger population with wider age groups. val recession were selected to assess the influence A review of the literature from 1982 to 2011 of predisposing factors. The reasons for these on the prevalence, extent, severity and associated exclusions were that gingival recession might be factors of gingival recession is summarised in related to young adults having orthodontic treat- Table 2. Studies targeting 15-32 year-old subjects ment [17,24]. Moreover, periodontitis is a bacterial [8,9,12,14,17,18] or this age group in a large popu- infection and inflammation, leading to bone lation [6,7,11] showed 29%-76% subjects were destruction along with an apical migration of junc- associated with at least one root-surface exposure tional epithelium. Periodontal surgery-including >1 mm and an extent of from 2%-18% of teeth. In the opened flap associated with root surface the current study, gingival recession was detected debridement and the apically repositioned flap for in 72.5% of Vietnamese dental students with the eliminating pockets-can also lead to root-surface same age range. Indeed, this high prevalence was exposure [3]. Although gingival recession is more similar to that reported in France (76%) [12], Italy frequently observed in smokers than in non-smok- (64%) [8], Brazil (64%-77%) [6,7]. The extent of ers [7,10,13], the risk of gingival recession attribut- affected teeth in the current study (11.1%) was also able to smoking is still controversial [17,25]. in agreement with previous studies in France

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Table 2. Studies of prevalence extent, severity and associated factors of gingival recession (GR) (continued over) Authors Year Population Prevalence (% Extent (% teeth Associated Non-associated Study Country [males/females] subjects with GR) with GR) Severity factors factors Years of age (mean) Examined surfaces Most frequent teeth Tenenbaum 1982 100 dental students 76/100 (76%) 320/2725 (11.7%) - Attached Oral hygiene Cross-sectional France [68/32] Male = female First premolars gingiva status, fraenum 19-26 (21.7) Labial (r = -0.201, attachment P<0.05) Khocht et al. 1993 182 subjects (63%) - - Age, tooth - Cross-sectional USA 18-65 Male > female brushing frequency Serino et al. 1994 225 subjects (25%) 1373/5168 (26.6%) - Age, loss of Gingival Cross-sectional Sweden 18-65 18-29 years: (44%) 18-29 years: (7%) approximal inflammation and longitudinal Labial Upper first molars attachment and premolars (multiple regression model, P<0.01) Van Palenstein 1998 575 subjects Labial and lingual 20-34 years: (18%) Most Calculus - Helderman et al. Tanzania [350/225] 35-44 years: (31%) serious: (Pearson Cross-sectional 20-64 45-64 years: (51%) lingual correlation, surface of P<0.05), age lower incisors Checchi et al. 1999 55 dental students (64%) Left side (55%) - Tooth-brushing Age, Cross-sectional Italy [29/26] Male < female > right side (45%) (multiple gender 19-26 Labial Premolars regression model, P<0.05) Arowojolu 2000 491 subjects 137/491 (27.7%) - - Tooth Cross-sectional Nigeria [259/232] malalignment, - 16-82 chewing stick trauma, traumatic tooth-brushing, calculus Dodwad 2001 1200 GR patients Labial Mandibular Classification Tooth-brushing Cross-sectional India [804/396] anterior of Miller: method and - 15-24 teeth I (86.2%), tooth-brush type, II (11.8%), plaque and III (1.8%), gingival IV (0.6%) inflammation, malaligned teeth (chi-square test, P<0.001), fraenal pull Marini et al. 2004 380 subjects 338/380 (89%) 3526/9379 (38%) Classification Age - Cross-sectional Brazil [146/234] 20-29 years: (64%) 20-29 years: (13.9%) of Miller: > 20 Labial and lingual Mandible > Maxilla I (59.2%), Mandibular central II (2.8%), incisors III (32.5%), IV (5.6%) Susin et al. 2004 1586 subjects (83.4%) (43.5%) GR > 3 mm Cigarette smoking, Gender, race, Cross-sectional Brazil [719/867] 20-29 years: (76.5%) 20-29 years: 18.1% (51.6 %), supragingival dental visits, 14-103 Male = female Mandibular GR > 3 mm calculus (Wald socio-economic (37.9 ± 13.3) Labial and lingual incisors (22 %) test, P<0.05 and status relative risk ratio, P<0.05), age (P<0.01) Kozlowska et al. 2005 455 medical students 134/455 (29.4%) (5.1%) - Age, tooth-brush - Cross-sectional Poland 18-32 Male < female Premolars and and tooth-brushing, Labial lower canines and female gender incisors (multiple regression model, P<0.05)

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Table 2. Studies of prevalence extent, severity and associated factors of gingival recession (GR) (continued) Authors Year Population Prevalence (% Extent (% teeth Associated Non-associated Study Country [males/females] subjects with GR) with GR) Severity factors factors Years of age (mean) Examined surfaces Most frequent teeth Thomson et al. 2006 915 subjects 628/882 (71.2%) (4.6%) - - Age Longitudinal New [469/446] Labial and lingual Lower incisors Zealand 32 Slutzkey& Levin 2007 303 subjects (14.6%) (1.6%) GR = 1-2 mm Past orthodontic Dental plaque, Cross-sectional Israel [126/177] Male > female (79.5%), treatment and oral gingivitis, 18-22 Labial surface GR > 3 mm piercing (Fisher smoking (20.5%) exact test and Pearson chi-square test, P<0.01) Toker&Ozdemir 2008 831 subjects (78.2 %) (17.4%) GR = 3-4 mm Age, high fraenum, - Cross-sectional Turkey [294/537] Male > female Maxilla < Mandible (0.8 %), traumatic tooth- 15-68 (P<0.05) (P<0.05) GR > 5 mm brushing, smoking (32.2 ± 11.7) Labial and lingual Mandibular (0.2%) duration (multiple incisors and right regression model, canine P<0.05), male gender, dental plaque and calculus- Sarfati et al. 2010 2074 subjects (84.6 %) 2-5 teeth with GR GR = 1-3 mm Age, male gender, Diabetes, Cross-sectional France [1017/1057] Labial (29.2% subjects) (76.9 %), number of missing increase of body 35-65 (49 ± 9) 6-9 teeth with GR GR = 4-5 mm teeth, plaque mass index, (20.5% subjects) (5.9 %), index, gingival alcohol intake, > 10 teeth with GR GR > 6 mm bleeding index, dental visits (24.6% subjects) (1.8 %) tobacco consumption (multiple regression model, P<0.05) Chrysantha- 2011 344 GR patients Labial Maxillary molars Classification Tooth-brush type - kopoulos et al. Greece [165/179] of Miller: and brushing Cross-sectional 18-68 I (79.4%), method, dental (46 ± 3.8) II (15.3%), plaque and III (4%), gingival IV (1.2%) inflammation, malpositioned teeth (chi-square test, P<0.05) Nguyen-Hieu This study 120 dental students 87/120 (72.5%) 362/3269 (11.1%) GR = Keratinised High fraenum et al. Vietnam [60/60] Male < female Maxilla > Mandible 1.0-3.2 mm, gingiva (Pearson attachment Cross-sectional 19-25 Labial (P<0.01) Most serious: correlation, (22.3 ± 2.0) Premolars Upper right t-test, and canines chi-square test, (1.9 ± 1.2 mm) P<0.001), tooth and lower malposition right canines (chi-square test, (1.9 ± 1.3 mm) P<0.001)

(11.7%) [12] and Brazil (13.9%) [6]. Hence, the Although in the current study the prevalence of gin- findings seemed to be similar to those reported in gival recession was slightly higher in females than Europe and America but they were very different in males, this difference was not statistically signif- from those found in Asia (only 14.6% of 18-22 icant. This result was in agreement with the major- year-old subjects in Israel and 1.6% of teeth associ- ity of previous studies [7-9,12] excluding a study in ated with at least one root-surface exposure) [17]. Turkey [13], which found that males had more gin-

140 OHDM - Vol. 11 - No. 3 - September, 2012 gival recession than females. Moreover, the propor- and canine regions of upper right and lower right tion of affected teeth in the current study was statis- arches. A similar result was also observed in left- tically higher in the maxilla than in the mandible handed subjects: gingival recession was usually whereas two previous studies [6,13] reported an detected in their upper left and lower left arches opposite finding. This contradiction could be [32]. The majority of Vietnamese dental students explained by the assessment of gingival recession were right-handed, used soft/medium toothbrushes of both labial and lingual tooth surfaces in these and had a good level of oral hygiene. This suggest- two studies. Indeed, the frequent accumulation of ed a correlation between gingival recession and calculus on the lingual surface of lower incisors tooth-brushing. Moreover, because of the transi- increased the proportion of root-surface exposure tional site between anterior and posterior teeth, the in mandible [7,13,16]. Therefore, teeth most fre- specific position of canines in dental arch could quently associated with gingival recession also var- make them more susceptible to traumatic tooth- ied according to which tooth surfaces were exam- brushing. Although subjects with periodontitis, or ined. Studies assessing both labial and lingual sur- those who had undergone or had periodontal sur- faces have usually found that the most frequently gery, orthodontics, fixed prostheses and smoking affected teeth were mandibular incisors [6,7,13, were excluded from this study, other triggering/ 14,16] whereas studies assessing only labial sur- aggravating factors including traumatic tooth- faces have suggested premolars or upper first brushing and non-carious cervical lesions (abra- molars as most frequently associated with gingival sion, erosion) may be risks for bias. Indeed, tooth- recession [8,9,11,12,19]. Accordingly, maxillary brushing and an acidic diet are probably related to and mandibular premolars were most frequently both and dentine hypersensitivity and associated with gingival recession in the current may be associated with gingival recession that is study. The narrowest width of keratinised gingiva termed "healthy recession" [1]. Traumatic tooth- was also found in premolar regions. Moreover, the brushing can cause superficial damage of the gingi- study of Joshipura et al. (1994) suggested that gin- va usually termed "gingival abrasions". However, gival recession might be due to tooth-brushing the relevance of this phenomenon to gingival reces- force in premolars or debris/calculus accumulation sion remains unclear [33]. Nevertheless it is clear in molars [28]. A significant negative correlation that toothbrush abrasion may cause wear at the has also been found between gingival recession and CEJ, resulting in the destruction of the supporting dental plaque [29]. However, the role of calculus as periodontium and leading to gingival recession an aetiological factor or consequence of gingival [34]. recession is disputed [6]. Localising the MGJ was facilitated by mucosa Although many studies have confirmed the staining with 3% Lugol's iodine solution. Indeed, influence of toothbrush type, tooth-brushing Lugol staining has been widely used to detect method and tooth-brushing frequency on the inci- malignant changes in the cervix uteri and the dence of gingival recession [5,8,9,13,18,19], a sys- oesophagus [35], and recently has been used to tematic review by Rajapakse et al. (2007) conclud- detect epithelial dysplasia in oral mucosa [36]. This ed that data to support or refute this relation were staining produced a red-brown colour based on the inconclusive [30]. The highest level of evidence reaction of iodine with glycogen granules of oral leading to this conclusion was presented in just one mucosa whereas content glycogen was inversely abstract of an industry-sponsored randomised con- related to degree of keratosis, leading to keratinised trolled clinical trial and after presentation at a sci- gingiva unstained with Lugol's iodine solution entific conference, this full trial had not been pub- [35,36]. This iodine solution has also been used to lished [31]. Interestingly, in the current study it was measure the width of keratinised gingiva in previ- observed that the most serious gingival recession ous studies [20,37]. Lang and Löe (1972) found was found in right canines of both the maxilla and that in areas with less than 2 mm of keratinised gin- the mandible. According to the evaluation of root- giva, inflammation persisted in spite of effective surface exposure in left- and right-handed adults, oral hygiene and they suggested that at least 2 mm Tezel et al. (2001) suggested the relationship of keratinised gingiva was necessary to maintain between gingival recession and the hand used in gingival health [37]. Only one longitudinal study tooth-brushing. In right-handed subjects, denuded has demonstrated that in patients maintaining prop- root surfaces were frequently detected in premolar er plaque control, lack of an adequate zone of

141 OHDM - Vol. 11 - No. 3 - September, 2012 attached gingiva did not result in the increased inci- not appear to be associated with predisposing fac- dence of gingival recession [20] whereas several tors. Therefore, further studies will be needed to cross-sectional studies have confirmed a correla- investigate the issue further. tion between the decreased width of keratinised/ attached gingiva and soft-tissue recession [12,38]. Conclusions In the current cross-sectional study, statistical tests This pilot study performed in a small population of showed a strong negative correlation between the dental students with high awareness of dental care lack of keratinised gingiva and root-surface exposure may not be representative of the whole population in subjects with good oral hygiene. Additionally, of the Vietnamese young adults. However, some teeth with narrow width of keratinised gingiva had preliminary conclusions may be drawn: a statistically higher prevalence of gingival reces- • A high prevalence of gingival recession sion than teeth without. However, it cannot be con- (72.5%) was found in 19-25 year-old cluded from these findings that a narrow width of Vietnamese dental students with 11.1% keratinised gingiva was a cause or a consequence extent of affected teeth. of gingival recession. Further longitudinal studies • The proportion of root-surface exposure are required to investigate this question. was statistically higher in the maxilla Malaligned teeth had a statistically higher pro- (12.5%) than in the mandible (9.6%). portion of root-surface exposure than those in a • Premolars were most frequently associated normal position. This finding was in accordance with gingival recession and right canines with previous studies [15,18,19]. It was seen that were the most severely affected teeth. tooth malposition, including rotation and lingual • There was a strong negative correlation inclination, was usually associated with soft debris between a narrow width of keratinised gin- retention and calculus because of difficult access giva and soft-tissue recessions. during tooth-brushing. Labially inclined teeth were • Root-surface exposure was statistically often susceptible to traumatic tooth-brushing and associated with tooth malposition. appeared to be more susceptible to non-carious cer- • Gingival recession was not associated with vical lesions. Furthermore, if a tooth erupts close to high fraenal attachment and gender. the MGJ, there is probably very little or no kera- Further studies performed in a larger popula- tinised gingiva labially and then gingival recession tion of non-dental students with more extended age can occur [3]. groups are required to confirm these findings. In the current study, no correlation was found between high fraenal attachment and root-surface Acknowledgements exposure. This finding was similar to that from a The authors would like to thank Dr. Trong-Hung study in France which also showed a low propor- Hoang (Department of Community , tion (3%) of affected teeth with high fraenal attach- Faculty of Odonto-Stomatology, University of ments [12]. However, high fraenal attachments Medicine and Pharmacy of Ho Chi Minh City, have been reported as significantly associated with Vietnam) for the statistical analysis. gingival recession in two previous studies [13,18]. It has been suggested that gingival/papillary fraenal attachments could impede access for plaque Author contributions removal [13] and that fraenal pull due to lack of • T N-H and B-D H-T conceived and attached gingival is also a factor causing gingival designed the study. recession [18]. Although the fraenal attachment has • B-D H-T and H D-T performed the clinical been reported as influencing plaque accumulation examinations. and gingivitis [39], in well-motivated individuals • T N-H and H T-G wrote the paper. with good oral hygiene (such as the dental students who took part in the current study) this influencing Conflict of interest and source of funding factor for gingival recession can be reduced or The authors declare that they have no conflicts eliminated. A key finding in the current study was of interest and no funding source. that 60.5% of teeth related to gingival recession did

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